[GreenKeys] Fwd: Current Loop

[Chris Elmquist]

I think he needs to have a model C 88-SIO board, which has support for 20mA
loop.  The A model is RS232 and then he'll need a converter.  The manual
for the 88-SIO_2 is here,

http://vt100.net/mirror/harte/Altair/MITS%2088sio_2%20Serial%20Card.pdf

and on page 6 it discusses how to connect to a teletype.


I think I saw his posting on the Stockley Altair replica site and I
tried to reply but I think my posting got lost.

Chris N0JCF

On Monday (07/20/2009 at 07:44PM -0400), Teletypeparts at aol.com wrote:
> 
> Hey Guys, 
>  
> I am forwarding a message I got from Tom Lake who has a 33 he got from  me. 
>  Can anybody help him with the problem he is having hooking up the 33  to 
> his Altair?  The 33 is wired for full duplex (4 wire) and he can make  the 33 
> receive work OK, but I am not familiar with the Altair hook up as he  
> describes it.  
>  
> Thanks,
>  
> Wayne
> KB1FDW
> 
> 
> From: thomas.lake at srmt-nsn.gov
> To:  Teletypeparts at aol.com
> Sent: 7/20/2009 2:04:56 P.M. Eastern Standard  Time
> Subj: Current Loop
> 
> 
> Hi, Wayne!
> 
> Remember me?  I  bough a Teletype from you a while back.
> 
> It's still working fine with my  PC but now I'd like to use it with
> my old Altair 2SIO serial interface board  which is supposed to handle
> 20 mA Current Loop OK.  The problem is the  teletype prints from the 
> computer
> but won't input to the computer.  I  know the TTY is good because, as I 
> said,
> I can use it with my computer with  no problem for input and output.
> Is this a problem with active/passive  loops?  Is there a way to change the 
> TTY
> to allow one or the other  on both TX and RX?  I don't see a way to change 
> the
> 2SIO board to do  that so I'd like to adjust the TTY if possible.
> Do you have any other  ideas?
> 
> Thanks for any help you may be able to give.
> 
> Tom Lake
>  
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-- 
Chris Elmquist